Hands down building, like M.Red,... There are really a few games where you can build what you want, where you want... Minecraft is the best, valheim is not far behind...
https://steamcommunity.com/sharedfiles/filedetails/?id=2787507761

Fishing, probably. Kind of a game within a game.

what i absolutely love about the game is the enviroment - often i found myself looking at the enviroment especially when the "godrays" shine thru trees, or when the moon does the same thing at night. Valheim provides the most immersive weather effect AND the coolest ocean
(and yeah, i honestly enjoy sailing my ship thru a storm ) its awesome

and of course - the bazillion ways one could build a nice home allmost everywhere
https://steamcommunity.com/sharedfiles/filedetails/?id=2788754759
... sometimes i cheat a bit for cosmetic reasons only ...

Cooking

They've nailed the setting - the music and visuals.
Gameplay, exploration and progression is excellent too. Tough to pinpoint just one aspect.

The one thing I like the most about this game is the ambience. This has a branch-out effect too. Since the ambience is so well made, it makes exploring, going out, and coming back home much more enjoyable.

For example, many people hate sailing and think it's tedious, but I love sailing in the sense that it's immersive. While I am taking 15-25 minutes to cross great distances, I am reading the news, watching Star Trek TNG, chatting on Whatsapp, etc on my 2nd monitor, occasionally looking back at my 1st monitor. If I am focused primarily on the game while travelling great distances, my mind wanders into a sort of role playing mentality. "I can't wait until I get back home to share my loot with the clan. (I play with 8 other people)" "I will get home, set my gear down, put some logs into the pit, and brew up some soup, then rest for the night." Etc.

The ambience also seeps into almost everything else too: fighting, defending, running away, dying, being surrounded, escaping, etc. It's all very well done.

For my list of things I don't like: https://steamcommunity.com/app/892970/discussions/0/3266806084899184757/?ctp=2#c3266806084899715548

Hands down, sailing. It's so well done, and so very engaging. You feel so involved in it, and there is definitely a learning curve to it. Each boat serves it's own purpose;

Karves are good for exploring and discovering new land, taking rivers to the heart of landmasses, and making even the tightest turns in the smallest of cove.

Longships are good for long cargo hauls, whether transporting silver or iron, and they can brave the fiercest of storms and conquer the mightiest waves of the ever-churning ocean. In a Longship one has such confidence to hunt dozens of serpents, and the hunter is in command of a heavy vessel of beautifully carven wood, worthy of legend.

And rafts, well, erm. They work well as small ferries! Maybe for rowing a small distance? Plop one in a river as a way across?

And the wind, oh the beautiful wind, you need to pay attention to it, and work with it, not against it. There have been several times when I've had impromptu expeditions because the wind was blowing the right direction one day. It's so satisfying to unfurl your sail, let it go on a beam reach, and off you go, off to navigate the seas!

Great topic!! :P
Farming, gathering, building (so so), sending greylings flying once you reach a certain point and one shooting Trolls hahaha! I cant name a single ONE thing I love about this game because there is too much to love :)

I love the persistence.

Thanks to mods, objects I throw on the grounds stay there essentially indefinite. I can drastically change and build the landscape with unique buildings and they'll stay there. I can level a whole forest and look at the stumps, which is very satisfying. Tombstones, everywhere; wish they stayed upon pickup aha.

I wish I had a better gpu so I could see my creations render in from a good distance, but running around finding things I half built and forgot is great.

It would be nice if things like stones/wood branches/dandilions didn't just spawn in the same spot and either spawned around tree stumps/trunks/open fields rather than like ontop of my wooden floor.

The sense of progression. I love how scary a new biome is until you farm all the mats from it and then crush it.

Hunting in the Alps. And sailing.

But there isn't one thing. Valheim is multiple games in one. At times it's pure twitch. At other times, all planning and logistics. At all times, fun.

Serpent hunting at night! I still get goosebumps from jumping in the ocean for the meat!

Ambience! love the sound and light drops.. jump scares.. As a keen bushwalker..silence is more scary than noisy... silence means predators!!

I love the views, the lighting effects and terrain look so beautiful. It looks especially great when sailing or looking down from a huge mountain.

The sight of a long ship under full sail on an open sea beneath a clear azure sky.